This proposal emphasizes the combined efforts and talents of a number of established investigators, each having diverse research interests, in a study of the effects of drugs of abuse on the behavior of rhesus monkeys. A unique opportunity is available to conduct such a study using enclosed social groups of monkeys in the colony at La Parguera, Puerto Rico. The specific objective of the proposal is to study the effects of delta 9-tetrahydrocannabinol, an active constituent of marihuana, on the social and sexual behavior of semi-free ranging rhesus monkeys. The effects of chronic medication of the drug at various dose levels on the monkey itself and on how it affects its social and sexual interactions with other group members will be studied. Considerable effort will be spent during the initial portion of the grant period to develop models for testing other drugs of abuse on the social behavior of free ranging monkeys. For example, attempts will be made to train monkeys to present themselves for intramuscular injections of other drugs of abuse. In later portions of the project the methodology developed concurrently while testing delta 9-THC will be employed to test other drugs of abuse, such as heroin.